Vehicle tires of all sizes are originally formed in molds wherein heat and pressure are applied to cure and mold the rubber employed in the tires. During use the tread of a tire is worn down and it is economically advantageous to apply new tread to undamaged tire carcasses. This new tread or retreading of the tire has in the past been normally accomplished by vulcanizing raw rubber to a buffed tire carcass in a pressurized mold by the application of heat to form new tread on the carcass.
There have been developed various improvements in tire recapping directed in part to the retreading or recapping of tires without the necessity of employing a pressurized mold. The problem of tire recapping molds becomes acute when dealing with very large sized pneumatic tires such as those employed on off the road vehicles like dirt movers and the like. Such tires may have a tread width of 2 to 3 feet or more with a tread diameter of 6 to 8 feet and larger. The original cost of tires this size may be of the order of $5,000 a piece so that recapping or affixing new tread thereto is almost an economic necessity. In the absence of recapping molds of these sizes, it has been conventional to apply new tread by hand by physically pounding raw rubber, tread lugs and spacers onto a buffed tire carcass and then to vulcanize the new tread thereon.
This procedure is quite time-consuming and normally requires a considerable number of man hours per tire while at the same time including numerous limitations which are undesirable from the viewpoint of the results achieved.
There have been developed methods of applying raw rubber to a buffed tire carcass very rapidly and precisely so that the rubber can then be vulcanized to the carcass as a smooth layer thereon. Tread lugs are then formed in the new rubber by cutting away portions thereof. A lengthy and expensive cutting operation is required and additionally the rubber removed during this cutting must be discarded for it has already been cured.
The present invention provides for the first time method and apparatus for applying raw rubber to a tire carcass and cutting the tread and the raw rubber prior to vulcanizing the rubber to the carcass.